Method of making synthetic fibre felt



Feb. 22, 1966 F. s. DARUWALLA 3,235,935

METHOD OF MAKING SYNTHETIC FIBRE FELT Filed May 14, 1963 United States Patent 3,235,935 METHOD OF MAKING SYNTHETIC FIBRE FELT Faredoon Shapurji Daruwalla, deceased, late of Sutton Coldfield, England, by Dolly Faredoon Daruwalla and Brian Michael Parlour, administrators, Sutton Coldfield, England, assignors to Dunlop Rubber Company Limited, London, England, a British company Filed May 14, 1963, Ser. No. 280,772 16 Claims. (Cl. 28-721) This invention relates to an improved man made fibre felt.

It has been proposed to produce a felt by needling a web of man made staple fibres by a needle-loom process in which the web is pierced by barbed needles which carry tufts and fibre ends through the web.

An object of the invention is to provide improved felts for use as carpeting and as paper makers blankets and for filtration where uniformity of the felt is of importance, for tennis ball covers, vibration mountings and similar applications.

According to the invention a felt comprises a mat of interpenetrated substantially aligned crimped continuous man made fibres.

The invention includes a method of making a felt which comprises assembling extended continuous man made fibres in substantially aligned relationship, relaxing the fibres into a crimped condition and needling the resultant mat of fibres with barbed needles.

The fibres may be crimped and then assembled under tension, the tension subsequently being removed thus allowing the crimped fibres to relax and intermingle with one another in sheet form. This is particularly applicable when using thermoplastic yarn which is crimped in any convenient manner, e.g. by false twisting, in which the yarn is twisted, heat set, and untwisted; by stutter box treatment, in which the yarn is heated in a crushed condition, for example, by feeding into a heated chamber with a smaller exit than inlet hole; by edge crimping, in which the yarn is heated and drawn over a sharp edge; or by passing the yarn between heated fluted rollers. Nonthermoplatsic yarn such as rayon may be crimped by cross-linking, for example using a crease-resisting urea formaldehyde resin or by steam setting in lieu of the heat setting step employed in the case of thermoplastic yarn. The fibers are usually drawn from a creel frame or warp beam, subjected to crimping and assembled together prior to relaxation.

Fibres having a potential crimp may be assembled and the crimp developed in the substantially aligned fibres so that they relax and intermingle one with another. For example, fibres spun from two polymers by a conjugate jet or rayon having an unbalanced skin structure, the skin either being ruptured or having more serrations on one side than on the opposite side, may be relaxed into a crimped condition by wetting; or nylon having disulphide and polyalkylene sulphide cross-links may be assembled whilst wet and relaxed into a crimped condition by drying off the swelling medium such as a mixture of methyl and benzyl alcohols.

Usually the fibres are assembled in the form of substantially twist-free yarn, and are condensed into a tow which is tensioned and spread out prior to relaxing the fibres in sheet form. The tow may be passed sinuously around a series of rollers from a tensioning device such as a series of lease rods, and passed from the rollers to an arcuate spreader such as a rod or a cambered roller.

The extended fibres, either crimped and tensioned or potentially crimped, may be let off a warp beam through a pair of nip rollers into a relaxing zone from which a mat of crimped intermingled but substantially aligned Fee fibres is passed, with reduced take up over a perforated bed beneath a rising and falling beam on the underside of which is attached a board having rows of closely spaced barbed needles.

A warp sheet of untwisted continuous filament thermoplastic yarns may be heated, for example, over a hot plate or by passage through a fluid bed, the filaments crimped by passing the sheet over a sharp edge, for example, at an included angle of about 28 degrees over an edge of about 15 microns radius, and then relaxed and the resultant mat needled as described above.

The mats may be felted by needling by themselves and two or more webs may be superposed, usually prior to needling. Some continuous filament yarn may be traversed over the surface of a mat, thus producing novel patterning effects in the felt produced, and the crimped yarns may be aligned in a mutually traversing arrangement instead of in parallel formation. The pattern may be produced by using yarns of different colours or by using yarns of different material e.g. nylon and polyethylene terephthalate available as Terylene, and subsequently cross dyeing the felt produced.

Additionally the mats may be assembled with and needled onto a base sheet of knitted or woven fabric, or non-woven felt which may be bonded by a binding agent, or of plastic or rubber and, if desired, binding agents such as thermoplastic resins may be added to the yarns or to the assembly before, during or after needling. Felts such as needleloom carpeting may be produced by applying a binding agent or sheet over the base sheet after needling.

The degree of hardness of the felts produced may be increased by increasing the number of needle punches and where soft felts are desired the depth of penetration of the needles may be reduced during part of the needling operation.

Felts produced according to the invention exhibit less pilling than is usually encountered with conventional felts made from man made fibres. Pilling is a serious problem with fabric made from staple fibres; the fibres migrate to the surface and form small balls which are anchored to the surface. This is especially prevalent with gnaterials in which the fibres are loosely twisted, such as e ts.

The invention will be described with reference to the following examples:

Example I Twistless continuous filament nylon 66 yarns nominally of 840 denier weight and having 280 filaments in all of about 3 denier per filament were processed on a false twist crimping machine. The speed of rotation of the false twist spindle was 15,500 revolutions per minute; yarn feed rate 57.3 ft./minute and yarn take-up rate 54.3 ft./minute giving an overfeed of about 5.5 percent; the heater temperature was 250 C.

A warp sheet of the resultant crimped yarns, which had about 4648 ends per inch, was then relaxed without tension at about C. in order to remove all stresses and strains introduced during the processing operations and in order to realise the full crimping potential of the filaments of the yarn. Thus, a fibre mat was produced which was uniform in weight and density and in which the individual filaments of the yarns were intermingled with one another.

The relaxed Web of crimped nylon yarn was then backed on to a knitted cotton fabric of 4 oz./sq. yd. weight and the web and the backing fabric were put through a needle machine which was adjusted to give about 300 punches per square inch; this operation was repeated four more times on the same length of the felt to increase consolidation of the product which was now felt-like in character and appearance. The resultant felt was 0.15 inch thick and 19 oz./ sq. yd. weight.

For purposes of comparison a nylon 66 staple fibre 60 mm. long having filaments of 3 denier weight was processed on a carding machine to produce webs in the conventional manner. Five of these carded webs were then cross-laid on the same backing fabric of 4 oz./sq. yd. weight, to give a web of approximately the same weight as above. This was in turn processed on the needle punching machine for the same number of punches as above. The resultant felt was 0.18 inch thick and 20.0 oz./ sq. yd. in weight.

It was observed that the staple fibre felt was more prone to delamination, tufts of fibres could be extracted much more readily and the fibre pilled easily upon slight abrasion.

In the following examples warp sheets 1, 2 of crimped yarns 3 in the extended state, as in the previous example, were produced by drawing the yarns from a creel frame through a crimping device and were condensed by lease rods 10 of a regulator 11; the resultant tow 4 of yarns was passed sinously around seven driven rollers arranged in two banks 12, 13.

The tow 4 was allowed to spread in width as it proceeded around the rollers and from the rollers was passed over an arcuate spreading rod 14 and through a heating chamber 15 in which infra-red heaters 16 raised the temperature to 80 C. Upon leaving the rollers the tow 4 relaxed into a state resembling cotton-wool and the relaxation was developed in the heating chamber, the yarns intermingling with one another whilst remaining substantially aligned in the direction of travel of the mat of yarns produced. From the heating chamber 15 the mat 5 passed over a driven feed apron 17 to a needling head 18 which was reciprocated to cause barbed needles 19 to penetrate the web and produce a felt 6.

The felt was passed between take up rollers 20, 21 which were driven, together with the apron 17, at a rate less than that of the rollers 12, 13, usually in the surface speed ratio of 1:3. The gearing (not shown) of the take up roller and apron drive was variable in order to realize the potential crimp in the tow 4 to the best advantage by adjusting its overfeed into the heating chamber; development of the crimp was also affected by adjusting the temperature in the heating chamber.

Example II Twistless continuous filament yarn of nylon 66, nominally 1040 denier and having 68 filaments in all, of trilobal cross-section, was processed on a false twist machine. The speed of rotation of the false-twist spindle was 15,500 r.p.m.; yarn feed 57.3 ft./minute and yarn take-up rate, 56.3 ft./minute giving an overfeed of about 1.7 percent: the heater temperature was 255 C.

A warp of resultant crimped yarns which had 380 ends was then relaxed without tension, to one-fifth of the original yarn length, at about 80 C. and at the same time was expanded in width to about 12" in the relaxation zone of the machine.

The relaxed mat of crimped yarn made as described above, was then backed on to a woven cotton fabric of 1.6 oz./ sq. yd. weight made up as follows:

Threads per inch warp 45.0; weft 30.0 Count warp 32s; weft 36s Percent crimp warp 2.5; weft 7.5 Yarn twist per inch24 Z; weft 21 Z The relaxed crimped yarn mat and the cotton backing cloth were put through the needle punching machine, adjusted to give about 800 punches per square inch; this operation was repeated three more times on the same length of the felt, making a total of 3200 punches per square inch on the felt. The resultant felt was then pressed to the required thickness and finish. The result- 4 ant felt was 20.5 02/ sq. yd. in weight and was 0.12" thick.

Representative tennis ball cores were taken of characteristics necessary to provide the tennis balls within L.T.A. Specification for bound and compression. Using identical methods of production and manufacture tennis balls were made from the felt, made as above, and from a standard wool nylon tennis ball cloth. These balls were then tested on a standard endurance testing machine where the loss in weight of the balls, after repeated hitting for 60 minutes was measuredthe standard melton covered balls lost 1.6 gram in weight whereas the continuous filament crimped nylon felt lost only 0.6 grrns. in weight. All other properties such as bound and compression were within the L.T.A. Specification.

Example III Twistless continuous filament nylon 66 yarns nominally of 840 denier and having 140 filaments in all of about 6 denier per filament were processed on an edge crimping machine. In essence the yarns were passed over a hot-plate (thermostatically controlled at 200 C.) at a tension of about 0.1 gm./denier and over a knife edge. The angle of approach of yarn to the knife edge was 21 and the yarn output angle was 7.

A warp of the yarns processed as described above and which had about 480 ends was then relaxed without tensionto one-third of the original yarn length, at about C. and at the same time was expanded to about 12" width in the relaxation zone of the machine. The relaxed mat of crimped yarn thus made was backed on to a woven nylon fabric of the following construction: Weight; 2.0 oz./'sq. yd.

Threads per inch warp 11.0; weft 11.0 Denier warp 210/34 fibres; weft 210/34 filaments Yarn twist per inch warp 0.5 Z; weft 0.5 Z.

The relaxed crimped yarn mat and the nylon backing cloth were put through the needle punching machine in the manner described in Example II. The resultant felt was about 1.6 oz./sq. ft. The felt, after being given a smooth calendered finish was suitable for use as superfine wet end felt on a paper makers machine, which require, in addition to good water permeability, a softer and smoother surface to produce a smooth surface paper free of marks.

Example IV Twistless continuous filament nylon 66 yarns nomi nally of 840 denier and having 140 filaments in all of about 6 denier per filament were processed on an edgecrimping machine in the manner given in Example III, and a warp of the crimped yarn having about 600 ends was then relaxed without tensionto one-third of the original yarn length, at about 80 C. and at the same time was expanded to about 12" width, in the relaxation zone of the machine. The mat then proceeded to the needle punching machine and was needled at the rate of 800 punches per square inch. The same piece of felt was passed again through the needle punching machine. In this manner a basic felt was made which weighed about 2 oz. per sq. ft.

In the next operation four of the basic felts made as above were combined and passed through a needle punching machine four times in all, to obtain 3200 punches per square inch. The resultant felt then weighed 7.7 oz./sq. ft. It was then moistened with water and pressed on a platen press, the platens being heated at 120 C. The thickness of the felt when thus pressed was 0.5". In this manner, depending upon the pressure of the press, the density of the felt could also be easily controlled. This felt was suitable for sound deadening material, chassis strips, vibration mountings, oil and grease retention, and the like uses.

Example V Twistless continuous filament polypropylene yarn of 570 denier and having filaments in all was processed on a false-twisting machine. The speed of rotation of the false-twist spindle was 2 1,000 r.p.m.; yarn feed 57.3 ft./minute and yarn take-up rate 54.3 ft./minute giving an overfeed of about 5.5 percent; the heater temperature was 160 C.

A warp of resultant crimped yarns which had about 510 ends was then relaxed without tension to four-ninths (or 44.5%) of the original yarn length, at about 100 C. and at the same time was expanded in width to about 12", in the relaxation zone of the machine. The relaxed mat of crimped yarn thus made was passed five times through the needle punching machine to give 4000 punches per square inch. The resultant felt was lightly calendered. The final felt weighed about 8 oz./sq. yd. and was .025" thick and was suitable for use as a medium for filtering liquids.

Having now described the invention what is claimed is:

1. A method of making a felt which comprises assembling under tension in substantially aligned relationship continuous rnan-made fibres capable of being retracted into a crimped condition, relaxing the fibres into a crimped condition to form a mat in which the crimped continuous fibres extend substantially parallel to the longitudinal axis of the mat and effecting consolidation of the mat by needling with barbed needles.

2. A method as claimed in claim 1 wherein the fibres are condensed into a tow which is tensioned and spread out prior to relaxing the fibres in sheet form.

3. A method as claimed in claim 2 wherein the tow is passed sinuously around a series of rollers from a tensioning device.

4. A method as claimed in claim 3 wherein the tow is passed from the rollers to an arcuate spreader.

5. A method as claimed in claim 1 wherein the mat is assembled with and needled onto a base sheet.

6. A method as claimed in claim 1 wherein a binding agent is applied to the assembly.

7. A method as claimed in claim 1 wherein the fibres are drawn from a creel frame, subjected to crimping and assembled together prior to relaxation.

8. A method as claimed in claim 1 wherein the fibres are drawn from a warp beam subjected to crimping and assembled together prior to relaxation.

9. A method as claimed in claim 1 wherein the mat is compressed after needling.

10. A method as claimed in claim 9 wherein the mat is moistened and compressed at an elevated temperature after needling.

11. A method as claimed in claim 2 wherein the fibre-s are drawn from a creel frame, subjected to crimping and assembled together prior to relaxation.

12. A method as claimed in claim 11 wherein the tow is passed sinuously around a series of rollers from a tensioning device and is passed from the rollers to an arouate spreader.

13. A method as claimed in claim 1 wherein the fibres comprise thermoplastic fibres.

14. A method as claimed in claim 13 wherein the fibres comprise nylon fibres.

15. A method as claimed in claim 13 wherein the fibres comprise polyethylene terephthalate fibres.

16. A method as claimed in claim 12 wherein the fibres comprise nylon fibres.

References Cited by the Examiner UNITED STATES PATENTS 2,893,105 7/1959 Lau-terbach 28-72.2 2,910,763 11/ 1959 Lauterbach 2872.2 2,959,509 11/ 1960 Marshall 2872.2 2,978,785 4/ 1961 Wenzell et a1. 28-72.2 3,059,311 10/ 1962 Hoc'hberg 2872.2 3,077,657 2/1963 Wells 16-1169 3,085,309 4/ 1963 Olson 161--64 3,090,099 5/1963 Smith 2872.2

DONALD W. PARKER, Primary Examiner.

L. K. RIMRODT, Assistant Examiner. 

1. A METHOD OF MAKING A FELT WHICH COMPRISES ASSEMBLING UNDER TENSION IN SUBSTANTIALLY ALIGNED RELATIONSHIP CONTINUOUS MAN-MADE FIBRES CAPABLE OF BEING RETRACTED INTO CRIMPED CONDITION, RELAXING THE FIBRES INTO A CRIMPED CONDITION TO FORM A MAT IN WHICH THE CRIMPED CONTINUOUS FIBRES EXTEND SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF THE MAT AND EFFECTING CONSOLIDATION OF THE MAT BY NEEDLING WITH BARBED NEEDLES. 